The study of the neuroantigen-specific CD4 T cells that mediate multiple sclerosis (MS) and its murine model, experimental allergic encephalomyelitis (EAE), continues to be challenging in vivo. Our knowledge of the contribution these cells make to the autoimmune disease process is particularly incomplete when it comes to an understanding of their function in the central nervous system 9CNS) itself. A primary goal of this application is to progress toward measuring their numbers and cytokine production (the primary effector function of CD4 T cells) in murine EAE models, in the CNS, and other compartments such as the blood and extra-lymphoid tissues. In Aim 1 we propose to study the population kinetics of the autoimmune T cell response in the course of EAE measuring the numbers of T cells reactive to the neuroantigens MBP and PLP, or the foreign antigen, OVA, in various tissues including lymphoid tissues (lymph nodes, LN, and spleen), the blood, and the CNS at various time points after the disease inducing immunization. This will be done by ELISPOT analysis, by intracytoplasmatic staining, and by in situ hybridization for select cytokines. Our studies should shed light on the distribution of neuroantigen-specific T cells in the organism at various stages of the disease process and on the natural history of the dynamics and selection of the autoimmune T cell repertoire.